Combustion chamber cleaning and corrosion preventing agent

ABSTRACT

An alkaline cleaning composition suitable for removing deposits from combustion chamber and the like walls and for protecting such walls against corrosion is disclosed. The composition is in the form of an aqueous solution, or a liquid or dry concentrate and comprises as active ingredients A. A WATER SOLUBLE SILICATE AND B. AT LEAST ONE WATER SOLUBLE AMMINE COMPLEX OF Zn, Cd, Cu and Sn.

United States Patent 11 1 Meyer [451 Oct. 7, 1975 1 1 COMBUSTION CHAMBER CLEANING AND CORROSION PREVENTING AGENT [76] Inventor: Hans Meyer, Am Birnbusch,

Bechtheim, Taunus, Germany 22 Filed: July 5, 1973 211 App]. No.: 376,675

[30] Foreign Application Priority Data July 12, 1972 Germany 2234172 [52] US. Cl. 252/523; 106/14; 134/19;

134/20; 134/39; 252/87; 252/135; 252/387 [51] Int. Cl CllD 7/O4;C11D 7/14; C23G 1/16;

F23] 1/00 [58] Field of Search 252/87, 110, 133, 135, 252/387, 523', 134/19, 20, 39; 106/14 [56} References Cited UNITED STATES PATENTS 2,050,122 8/1936 Reuss 252/389 X 2,836,566 5/1958 Duncan .1 252/523 X 2,957,762 10/1960 Young l 252/387 3,096,169 7/1963 Shapiro, 252/387 X 3,580,934 5/1971 Murray l 4 4 11 252/387 X 3,645,905 2/1972 Rosenfeld 252/540 Primary ExaminerDennis E. Talbert, .lr. Assistant Examiner-Dennis L. Albrecht Attorney, Agent, or Firm-T0rn, McGeady and Stanger [57] ABSTRACT 12 Claims, N0 Drawings COMBUSTION CHAMBER CLEANING AND CORROSION PREVENTING AGENT FIELD OF INVENTION This invention relates to cleaning compositions for cleaning or removing deposits from the walls of combustion chambers, fire boxes, furnaces and the like and for protecting such walls against corrosion.

BACKGROUND INFORMATION AND PRIOR ART In the operation of fire boxes, such as oil or coal burning furnaces, or other combustion chamber comprising structures, the formation of soot and other deposits on the combustion chamber walls is unavoidable. Such deposits customarily comprise carbon and certain crust forming compounds such as sulfur compounds which present solid incrustations and exert a corroding influence on the combustion chamber walls. A number of cleaning agents or compositions having previously been proposed for the purpose of removing these corroding deposits. These cleaning agents customarily are sprayed or injected into the fire box or combustion chamber in the form of aqueous solutions which then exert a dissolving action on the deposits and which, in some instances, coat the respective walls with a layer which protects the walls against corrosion.

A cleaning agent of the indicated kind is for example disclosed in Swiss Pat. No. 360,072 which suggests an aqueous alkaline solution, particularly an aqueous sodium carbonate solution for this purpose, the solution being applied to the walls on the flue gas discharge side of the structure.

According to Swiss Pat. No. 280844, a corrosion protecting agent in the form of alkaline earth metal compounds, compounds of the rare earths or compounds of silicon, zirconium, thorium, hafnium, vanadium or silicates or aluminates is proposed which is injected into the combustion chamber space.

Other compositions of the nature referred to are disclosed in German Auslegeschrift No. l 810 424 and German Offenlegungsschrift No. l 817 798. These two publications are concerned with a procedure for the cleaning of furnaces or fire boxes with a solution of a mixture which thermally decomposes under the evolution of gas. The mixture comprises preferably compounds which, when heated, liberate ammonia and carbon dioxide and the mixture also comprises customary anionic. amphoteric or nonionogenic tensides.

French Pat. No. l 434 I60 teaches a corrosion preventing layer forming agent which comprises silicates, certain specified sulfates and phosphates. Still further cleaning agents for the indicated purpose are described in Austrian Pat. No. 255 628 and in German Offenlegungsschrift No. l 521 813. According to the latter teaching. the composition comprises metasilicates, chromates, nitrates and nitrites. Finally, German Offenlegungsschrift No. l 626 66l, in a manner similar to that of Swiss Pat. No. 280 844 previously referred to, is concerned with a cleaning agent which consists essentially of an aqueous solution of a mixture of water glass and magnesium oxide and which additionally may contain wetting agents.

Although these prior art cleaning agents exert a beneficial effect and in many instances have a sufficient dissolving action on the deposits on the walls, it has been ascertained that oftentimes the corrosion preventing effect of these compositions is inadequate and the walls to be protected against corrosion are still sufficiently exposed.

SUMMARY OF THE INVENTION It is a primary object of the present invention to overcome the disadvantages of the prior art cleaning compositions and to provide a cleaning composition of the indicated kind which not only has superior deposit removing characteristics but which also exerts an excellent corrosion preventing effect on the walls to which the composition is applied.

Generally, it is an object of the invention to improve on the art of cleaning agents and corrosion preventing agents as used in oil or coal burning structures as presently practised.

Briefly, and in accordance with this invention, the above objects are superiorly achieved by providing an alkaline cleaning composition which is in the form of an aqueous solution, or a liquid, pasty or dry concentrate and which comprises as active ingredients a. a water soluble silicate and b. at least one water soluble ammine complex of Zn,

Cd, Cu and Sn.

A composition of the indicated kind if sprayed or otherwise injected into a combustion chamber space exerts an excellent deposit removing action and protects the walls efficiently against corrosion.

As previously stated, the composition may be in the form of an aqueous solution or may be a concentrate, to wit, a dry powderlike substance or a paste or slurry.

In respect to ingredient (a), to wit, the water soluble silicate, it should be understood that the term water soluble" indicates that the silicate is completely or largely water soluble. Suitable water soluble silicates for the purposes of this invention are tha alkali metal or ammonium metasilicates, guanidine silicates or silicate mixtures, such as alkali metal or ammonium water glass. If a sodium water glass is used, it has been found that particularly advantageous results are obtained if the water glass has an Na- O:SiO ratio of 1:0.2 to 4.0.

The other effective ingredient in the inventive composition is a water soluble ammine (ammonium) complex of Zn, Cd, Cu and Sn. The complex may be prepared by reaction of a compound or salt of one of the indicated metals in aqueous solution by introducing into the solution gaseous ammonia or by the addition of concentrated or diluted aqueous ammonia solution in which the ammonia is present in the form of ammo nium hydroxide. Suitable ammonium complexes for the purposes of the invention are zinc tetraamminehydroxide, cadmium tetraamminehydroxide, cadmium hexaamminehydroxide, copper diamminechloride and copper tetraarnminehydroxide. It has been found that the best results are obtained with ammine complexes of zinc.

Concerning the quantity ratio between ingredient (a) and ingredient (b), it has been established that excellent results are obtained if the composition comprises 540 parts by weight of water soluble silicates and l to 10 parts by weight of ingredient (b), to wit, the amine metal complex. The ratio is thus 540: 1 to ID. Within the indicated range, superior results are obtained if 10-35 parts by weight of ingredient (a) are admixed with 2 to 8 parts by weight of ingredient (b). If ingredient (a) is present in 15 to 30 parts by weight, then ingredicnt (b) should preferably be present in 3 to 6 parts by weight.

The cleaning agent according to the invention may additionally contain alkali metal hydroxides, preferably in an amount of about 1 to 15, advantageously 2 to 8 or 3 to 5 parts by weight, in order to increase the alkalinity of the aqueous cleaning composition. Further, the presence of the alkali metal hydroxides serves the pur pose to adjust the water glass solutions to metasilicate or orthosilicate.

Further. it is also advantageous to admix the cleaning composition of the invention with a wetting agent which preferably should be present in amounts of 0.2 to 5 parts by weight per 5 to 40 parts by weight of the water soluble silicate. Such wetting agents may be in the nature of nonionogenic. cation active or anion active wetting agents. Advantageously, amphoteric wetting agents, well known in the art are used for this purpose. Examples for suitable wetting agents are for example alkylnaphthalinesulfonatcs. alkylarylsulfonates and their sodium salts, such as the sodium salt of dodecylbenzenesulfonate, sulfonated fatty acid esters, C -C -,-alkylsulfates, C C alkylpolyoxyethylene alcohols. ethylene oxide condensation product of alkylphenols, quaternary ammonium salts, such as octadecyldimethylbenzylammoniumchloride, or as amphoteric wetting agents. betaine derivatives. It will be appreciated that the specific nature of the wetting agents is not critical and the above are indicated by way of example only.

Finally, the cleaning agents according to the invention may additionally contain alkali metal or ammonium phosphates, chromatcs, nitrites and/or nitrates, preferably in an amount of 0.5 to l0, particularly of 2-5 parts by weight.

From a practical point of view, the inventive alkaline cleaning agents or compositions may be prepared as concentrate in solution which thus constitutes a master solution which may be diluted prior to use in order to form solutions which can be directly sprayed into the furnace structures.

Experience has demonstrated that, surprisingly, the inventive cleaning agents are also extremely stable for indefinite periods of time when stored in the form of aqueous solutions. When they are sprayed onto hot walls of combustion chambers and the like, they not only dissolve the incrustations and deposits but also form a well-adhering permanent corrosion preventing layer which essentially consists of the respective metal silicate, to wit, zinc, cadmium. copper or tin silicate, in a thickness of about 2 to lOu. This protective layer exerts a better and more permanent corrosion protecting effect than prior art compositions intended for the same purpose. Further, the inventive composition dissolves the deposits of combustion residues and thus effectively removes them therefrom so that the silicate layers can then directly form on and adhere to the cleaned wall surfaces.

The invention will now be described by several Examples, it being understood that these Examples are given by way of illustration and not by way of limitation and that many changes may be effected without affecting in any way the scope and spirit of the invention as recited in the appended claims.

EXAMPLE 1 A cleaning and corrosion preventing agent was prepared by mixing the following ingredients in the indicated percentages, the percentage values referring to percentages by weight.

Aqueous sodium hydroxide solution of 50% concentration 77r soda water glass (sodium silicate),

37f40Bc 20% zinc nitrate. anhydrous 3C? concentrated ammonia [aqueous solution of 25% concentration] 5% wetting agent lf r water 64)? ide solution, which were replaced by 12 to l57r of sodiummetasilicate. Essentially the same beneficial results were obtained.

EXAMPLE 2 A cleaning composition which also formed a film for protecting wall surfaces against corrosion was prepared by mixing the following ingredients in the same manner as in Example 1.

Aqueous potassium hydroxide solution of 57% concentration 7% Potassium water glass, 28/3U Be 3092 Concentrated ammonia (aqueous solution of 25% concentration) 5% Zinc nitrate, anhydrous 3% Wetting agent [9% Water 54% The solution thus formed was used as described in Example 1 with similar results. The potassium water glass and the potassium hydroxide can be replaced by 12 to 15% of potassium metsilicate, resulting in essentially the same effect.

EXAMPLE 3 A cleaning composition which also formed a film for protecting wall surfaces against corrosion was prepared by mixing the following ingredients in the same manner as in Example 1.

Aqueous sodium hydroxide solution of 50% concentration 7% Soda water glass, 37/40 Be 309 C oncentratcd ammonia (aqueous solution of 25% concentration) 8% Stanno hydroxide 571 Wetting agent 1% Water 49% The solution thus formed was used as described in Example 1 with similar results.

EXAMPLE 4 A cleaning composition which also formed a film for protecting wall surfaces against corrosion was prepared by mixing the following ingredients in the same manner as in Example 1.

Aqueous potassium hydroxide solution of 57% The solution thus formed was used as described in Example I with similar results.

EXAMPLE 5 A cleaning composition which also formed a film for protecting wall surfaces against corrosion was prepared by mixing the following ingredients in the same manner as in Example l.

Aqueous potassium hydroxide solution of 57% concentration 7 /r Potassium water glass, 28/30" Be INF/I Concentrated ammonia (aqueous solution of concentration) 6% Cadmium hydroxide 3.59? Wetting agent l'7r Water 52.57

The solution thus formed was used as described in Example 1 with similar results.

What is claimed is:

I. An alkaline cleaning composition suitable for removing deposits from combustion chamber and the like walls and for protecting such walls against corrosion, said composition being in the form of an aqueous solution or a liquid or dry concentrate and consisting essentially of:

a. a water soluble silicate and b. at least one water soluble ammine complex selected from the group consisting of Zn, Cd, Cu and Sn, wherein the weight ratio of ingredients (a) to (b) is between about 5 to 40:l to 10.

2. A cleaning composition as claimed in claim 1, wherein ingredient (a) is selected from the group consisting of alkali metal metasilieate, ammonium metasilicate, guanidinesilicate, alkali metal water glass and ammonium water glass.

3. A cleaning composition as claimed in claim 2, wherein said water glass has an Na O:SiO ratio of 4. A cleaning composition as claimed in claim I, additionally comprising a wetting agent in an amount of about 0.2 to 5 parts by weight per 5 to 40 parts by weight of ingredient (a).

5. A cleaning composition as claimed in claim 4, wherein said wetting agent is an amphoteric wetting agent.

6. A cleaning agent as claimed in claim 1, additionally comprising about 0.5 to l0 parts by weight of at least one member selected from the group consisting of alkali metal phosphates, alkali metal chromates, alkali metal nitrates, alkali metal nitrites, ammonium phosphates, ammonium chromates, ammonium nitrates and ammonium nitrites per 5 to 40 parts by weight of ingredient (a).

7. A cleaning composition as claimed in claim 1 wherein ingredient (b) is selected from the group consisting of zinc tetraaminehydroxide, cadmium tetraaminehydroxide, cadmium hexaamminehydroxide, copperdiamminechloride, and copper tetraamminehydroxide.

8. An alkaline cleaning composition suitable for removing deposits from combustion chamber and the like walls and for protecting such walls against corrosion, said composition consisting essentially of as effective ingredients:

a. a water soluble silicate selected from the group consisting of alkali metal metasilicate, ammonium metasilicate, guanidinesilicate, alkali metal water glass and ammonium water glass and b. an ammine complex selected from the group consisting of Zn, Cd, Cu and Sn,

said composition comprising 5 to 40 parts by weight of ingredient (a) and l to ID parts by weight of ingredient (b).

9. A cleaning composition as claimed in claim 8, which is in the form of an aqueous solution.

10. A cleaning composition as claimed in claim 8, further comprising about 0.2 to 5 parts by weight of a wetting agent and about 0.5 to 10 parts by weight of a member selected from the group consisting of alkali metal phosphate, alkali metal chromate, alkali metal nitrate, alkali metal nitrite, ammonium phosphate, ammonium chromate, ammonium nitrate and ammonium nitrite.

11. A cleaning composition as claimed in claim 8, wherein ingredient (b) is selected from the group consisting of zinc tetraamminehydroxide, cadmium tetraamminehydroxide, cadmium hexaamminehydroxidc, coppper diamminechloride and copper tetraamminehydroxide.

12. A cleaning composition as claimed in claim 6, further comprising about l to 15 parts by weight of an alkali metal hydroxide. 

1. AN ALKALINE CLEANING COMPOSITION SUITABLE FOR REMOVING DEPOSITS FROM COMBUSTION CHAMBER AND THE LIKE WALLS AND FOR PROTECTING SUCH WALLS AGAINST CORROSIN, SAID COMPOSITION BEING IN THE FORM OF AN AQUEOUS SOLUTION OR A LIQUID OR DRY CONCENTRATE AND CONSISTING ESSENTIALLY OF: A. A WATER SOLUBLE SILICATE AND B. AT LEAST ONE WATER SOLUBLE AMMINE SELECTED FROM THE GROUP CONSISTING OF ZN, CD, AND SN, WHEREIN THE WEIGHT RATIO OF INGREDIENTS (A) TO (B) IS BETWEEN ABOUT 5 TO 40:1 TO
 10. 2. A cleaning composition as claimed in claim 1, wherein ingredient (a) is selected from the group consisting of alkali metal metasilicate, ammonium metasilicate, guanidinesilicate, alkali metal water glass and ammonium water glass.
 3. A cleaning composition as claimed in claim 2, wherein said water glass has an Na2O:SiO2 ratio of 1:0.2 to 4.0.
 4. A cleaning composition as claimed in claim 1, additionally comprising a wettiNg agent in an amount of about 0.2 to 5 parts by weight per 5 to 40 parts by weight of ingredient (a).
 5. A cleaning composition as claimed in claim 4, wherein said wetting agent is an amphoteric wetting agent.
 6. A cleaning agent as claimed in claim 1, additionally comprising about 0.5 to 10 parts by weight of at least one member selected from the group consisting of alkali metal phosphates, alkali metal chromates, alkali metal nitrates, alkali metal nitrites, ammonium phosphates, ammonium chromates, ammonium nitrates and ammonium nitrites per 5 to 40 parts by weight of ingredient (a).
 7. A cleaning composition as claimed in claim 1 wherein ingredient (b) is selected from the group consisting of zinc tetraaminehydroxide, cadmium tetraaminehydroxide, cadmium hexaamminehydroxide, copperdiamminechloride, and copper tetraamminehydroxide.
 8. An alkaline cleaning composition suitable for removing deposits from combustion chamber and the like walls and for protecting such walls against corrosion, said composition consisting essentially of as effective ingredients: a. a water soluble silicate selected from the group consisting of alkali metal metasilicate, ammonium metasilicate, guanidinesilicate, alkali metal water glass and ammonium water glass and b. an ammine complex selected from the group consisting of Zn, Cd, Cu and Sn, said composition comprising 5 to 40 parts by weight of ingredient (a) and 1 to 10 parts by weight of ingredient (b).
 9. A cleaning composition as claimed in claim 8, which is in the form of an aqueous solution.
 10. A cleaning composition as claimed in claim 8, further comprising about 0.2 to 5 parts by weight of a wetting agent and about 0.5 to 10 parts by weight of a member selected from the group consisting of alkali metal phosphate, alkali metal chromate, alkali metal nitrate, alkali metal nitrite, ammonium phosphate, ammonium chromate, ammonium nitrate and ammonium nitrite.
 11. A cleaning composition as claimed in claim 8, wherein ingredient (b) is selected from the group consisting of zinc tetraamminehydroxide, cadmium tetraamminehydroxide, cadmium hexaamminehydroxide, coppper diamminechloride and copper tetraamminehydroxide.
 12. A cleaning composition as claimed in claim 6, further comprising about 1 to 15 parts by weight of an alkali metal hydroxide. 